MRI-compatible patches and methods for using the same

ABSTRACT

An MRI-compatible patch for identifying a location includes a flexible base layer, a flexible substrate and at least one of MRI-visible fiducial element. The flexible base layer is mountable on and substantially conformable to a patient&#39;s body surface. The base layer has opposed upper and lower primary surfaces. The flexible substrate is releasably attached to the upper primary surface of the base layer and substantially conformable to the patient&#39;s body surface. The at least one MRI-visible fiducial element is defined by or secured to the flexible substrate. The patch may include a plurality of the MRI-visible fiducial elements arranged in a defined pattern.

RELATED APPLICATION(S)

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 60/974,821, filed Sep. 24, 2007, the disclosureof which is incorporated herein by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to medical systems and methodsand, more particularly, to in vivo medical systems and methods.

BACKGROUND OF THE INVENTION

Deep Brain Stimulation (DBS) is becoming an acceptable therapeuticmodality in neurosurgical treatment of patients suffering from chronicpain, Parkinson's disease or seizure, and other medical conditions.Other electro-stimulation therapies have also been carried out orproposed using internal stimulation of the sympathetic nerve chainand/or spinal cord, etc.

One example of a prior art DBS system is the Activa® system fromMedtronic, Inc. The Activa® system includes an implantable pulsegenerator stimulator that is positioned in the chest cavity of thepatient and a lead with axially spaced apart electrodes that isimplanted with the electrodes disposed in neural tissue. The lead istunneled subsurface from the brain to the chest cavity connecting theelectrodes with the pulse generator. These leads can have multipleexposed electrodes at the distal end that are connected to conductorswhich run along the length of the lead and connect to the pulsegenerator placed in the chest cavity.

It is believed that the clinical outcome of certain medical procedures,particularly those using DBS, may depend on the precise location of theelectrodes that are in contact with the tissue of interest. For example,to treat Parkinson's tremor, presently the DBS probes are placed inneural tissue with the electrodes transmitting a signal to the thalamusregion of the brain. DBS stimulation leads are conventionally implantedduring a stereotactic surgery, based on pre-operative MRI and CT images.These procedures can be long in duration and may have reduced efficacyas it has been reported that, in about 30% of the patients implantedwith these devices, the clinical efficacy of the device/procedure isless than optimum. Notwithstanding the above, there remains a need foralternative MRI-guided interventional tools for DBS, as well as forother interventional medical procedures.

SUMMARY OF THE INVENTION

According to embodiments of the present invention, an MRI-compatiblepatch for identifying a location includes a flexible base layer, aflexible substrate and at least one MRI-visible fiducial element. Theflexible base layer is mountable on and substantially conformable to apatient's body surface. The base layer has opposed upper and lowerprimary surfaces. The flexible substrate is releasably attached to theupper primary surface of the base layer and substantially conformable tothe patient's body surface. The at least one MRI-visible fiducialelement is defined by or secured to the flexible substrate. TheMRI-visible fiducial elements are arranged in a defined pattern.

According to some embodiments, the patch includes an adhesive toreleasably attach the flexible substrate to the base layer.

The patch may include an adhesive disposed on the lower primary surfaceof the base layer to attach the base layer to the body surface.

The patch may include indicia on the base layer corresponding to theMRI-visible fiducial elements on the flexible substrate. The patch mayinclude second indicia on the flexible substrate corresponding to theindicia on the base layer.

In some embodiments, the patch includes a plurality of the MRI-visiblefiducial elements. The fiducial elements may be arranged in a definedpattern. Indicia may be provided on the base layer corresponding to theMRI-visible fiducial elements on the flexible substrate, wherein theindicia has a second prescribed pattern having a higher resolution thanthe defined pattern of the MRI-visible fiducial elements on the flexiblesubstrate. In some embodiments, the defined pattern includes a gridpattern defining a coordinate system. The patch may include codifiedindicia representing the coordinate system.

The flexible substrate can include a pull tab to facilitate removal ofthe flexible substrate from the base layer.

In some embodiments, the base layer is frangible to permit selectiveaccess to the body surface when the base layer is mounted thereon andthe flexible substrate has been at least partially removed.

According to some embodiments, the patch includes at least oneMRI-visible reference indicator to indicate an orientation of the patch.

In some embodiments, at least one of the MRI-visible fiducial elementshas a first MRI-visible geometric shape, and at least one of theMRI-visible fiducial elements has a second MRI-visible geometric shapedifferent from the first MRI-visible geometric shape.

According to some embodiments, at least some of the MRI-visible fiducialelements include a pocket containing MRI-visible material. TheMRI-visible material may include an MRI-visible liquid.

At least some of the MRI-visible fiducial elements may be selectivelydiscretely removable from the flexible substrate to permit access to thebody surface.

According to some embodiments, the patch includes perforations definedin the flexible substrate to thereby enhance conformity of the flexiblesubstrate to the body surface.

The flexible substrate can be formed of a stretchable material to allowthe flexible substrate to conform to a head body surface.

According to some embodiments, the flexible substrate has a thickness inthe range of from about 0.001 to 0.100 inches.

According to some embodiments, the flexible substrate is a substratematerial selected from the group consisting of polyvinyl, PET, silicone,polyethylene, polyurethane, and polyamide.

According to some embodiments, the patch further includes: a pluralityof MRI-visible fiducial elements defined by or secured to the flexiblesubstrate, wherein the fiducial elements are arranged in a definedpattern; an adhesive disposed on the lower primary surface of the baselayer to attach the base layer to the body surface; a release linerbacking and releasably secured to the adhesive; and indicia on the baselayer corresponding to the MRI-visible fiducial elements on the flexiblesubstrate; and at least one MRI-visible reference indicator to indicatean orientation of the patch; wherein at least some of the MRI-visiblefiducial elements include a pocket containing MRI-visible liquid, andwherein the defined pattern includes a grid pattern defining acoordinate system.

According to embodiments of the present invention, a method foridentifying a physical location on a body surface of a patient includesproviding a patch including: a flexible base layer that is mountable onand substantially conformable to a patient's body surface, the baselayer having opposed upper and lower primary surfaces; a flexiblesubstrate that is releasably attached to the upper primary surface ofthe base layer and substantially conformable to the patient's bodysurface; and at least one MRI-visible fiducial element defined by orsecured to the flexible substrate. The method further includes: securingthe base layer to the body surface to mount the patch on the bodysurface such that the flexible substrate conforms to the body surface;MRI scanning the patient with the patch on the body surface to generatecorresponding image data; identifying a physical location on the bodysurface using the image data; and removing the flexible substrate fromthe base layer.

According to some embodiments, the patch includes a plurality of theMRI-visible fiducial elements. In some embodiments, the fiducialelements are arranged in a defined pattern.

According to embodiments of the present invention, a method foridentifying a physical location on a body surface of a patient residingin physical space includes providing a patch residing in physical spaceand including: a flexible substrate that is mountable on andsubstantially conformable to the body surface; and at least oneMRI-visible fiducial element defined by or secured to the flexiblesubstrate. The method further includes: mounting the patch on the bodysurface such that the flexible substrate conforms to the body surface;MRI scanning the patient with the patch on the body surface to generatecorresponding image data; and identifying a physical location on thebody surface using the image data, including: generating an image of thepatient in a logical space; determining in the logical space a desiredentry location on the body surface for insertion of instrumentation intothe patient; and programmatically determining a physical location on thepatch corresponding to the desired entry location.

In some embodiments, determining in the logical space the desired entrylocation includes determining a desired trajectory line, and determiningthe physical location on the patch corresponding to the desired entrylocation includes determining a location of intersection between thedesired trajectory line and the patch. The method may includeprogrammatically determining in the logical space the desired entrylocation and the desired trajectory line. The method can includedisplaying the desired entry location and the desired trajectory line ona display device to an operator.

According to some embodiments, the patch includes a plurality of theMRI-visible fiducial elements. In some embodiments, the fiducialelements are arranged in a defined pattern. According to someembodiments, the method includes displaying the image of the patient anda graphical overlay on a display to an operator. The graphical overlayindicates at least a portion of the defined pattern of the MRI-visiblefiducial elements.

The method may further include marking the body surface at a locationcorresponding to the physical location on the patch.

According to some embodiments, the body surface is on the patient's headand the method includes forming a burr hole in the patient's skullproximate the physical location.

The mounting step may comprise releasably attaching the flexiblesubstrate to the body surface prior to the step of MRI scanning thepatient with the patch on the body surface. According to someembodiments, the patch includes a flexible base layer having opposedupper and lower primary surfaces, wherein the flexible substrate isreleasably attached to the upper primary surface of the base layer, andthe method includes: securing the base layer to the body surface priorto the step of MRI scanning the patient with the patch on the bodysurface; and removing the flexible substrate from the base layer afterthe step of MRI scanning the patient with the patch on the body surface.

The method may include removing at least one of the fiducial elementsfrom the flexible substrate after the step of MRI scanning the patientwith the patch on the body surface to permit access to the body surface.

In some embodiments, at least some of the MRI-visible fiducial elementsinclude a pocket containing MRI-visible material.

In some embodiments, the method includes: mounting a plurality of thepatches on the body surface in close proximity to one another; andthereafter MRI scanning the patient with the plurality of patches on thebody surface to generate corresponding image data.

According to some embodiments, MRI scanning the patient with the patchon the body surface includes MRI scanning an MRI-visible referenceindicator on the patch to generate corresponding reference image data.The method further includes programmatically determining an orientationof the patch using the reference image data.

According to embodiments of the present invention, a computer programproduct for identifying a physical location on a body surface of apatient using a patch mounted on the body surface and including at leastone MRI-visible fiducial element includes a computer readable mediumhaving computer usable program code embodied therein, the computerreadable program code comprising: computer readable program codeconfigured to generate an image of the patient and the patch in alogical space, the image corresponding to an MRI scan of the patientwith the patch on the body surface; computer readable program codeconfigured to determine in the logical space a desired trajectory linefor insertion of instrumentation into the patient; and computer usableprogram code configured to programmatically determine a location ofintersection between the desired trajectory line and the patch.

According to embodiments of the present invention, a system fordesignating a physical location on a body surface of a patient includesa patch and a controller. The patch includes: a flexible substrate thatis mountable on and conformable to the body surface; and at least oneMRI-visible fiducial element defined by or secured to the flexiblesubstrate. The controller is adapted to communicate with an MRI scannerthat is operable to scan the patient with the patch on the body surfaceand to generate corresponding image data. The controller processes theimage data from the MRI scanner to programmatically identify a physicallocation on the body surface.

In some embodiments, the controller is operable to display correlatedrepresentations of the at least fiducial element and the patient.

According to embodiments of the present invention, a medical (surgical)kit for designating a physical location on a head of a patient includesa patch and a head marking tool. The patch includes a flexible baselayer, a flexible substrate and at least one MRI-visible fiducialelement. The flexible base layer is mountable on and substantiallyconformable to a patient's body surface. The base layer has opposedupper and lower primary surfaces. The flexible substrate is releasablyattached to the upper primary surface of the base layer andsubstantially conformable to the patient's body surface. The MRI-visiblefiducial element is defined by or secured to the flexible substrate. Thehead marking tool is configured to mark the head of the patient.

In some embodiments, the head marking tool is configured to mark a skullof the patent.

According to embodiments of the present invention, an MRI-compatiblepatch for identifying a location includes a flexible substrate that ismountable on and substantially conformable to a patient's body surface.A plurality of MRI-visible fiducial elements are defined by or securedto the flexible substrate. The MRI-visible fiducial elements arearranged in a defined pattern. The plurality of MRI-visible fiducialelements include at least one MRI-visible reference indicator toindicate an orientation of the patch.

According to embodiments of the present invention, a method foridentifying a physical location on a body surface of a patient residingin physical space includes providing a patch residing in physical spaceand including: a flexible substrate that is mountable on andsubstantially conformable to the body surface; and at least oneMRI-visible fiducial element defined by or secured to the flexiblesubstrate. The method further includes: mounting the patch on the bodysurface such that the flexible substrate conforms to the body surface;MRI scanning the patient with the patch on the body surface to generatecorresponding image data; generating an image of the patient in alogical space; and programmatically determining an orientation of thepatch in the logical space using the image data.

In some embodiments, the patch includes an MRI-visible referenceindicator and programmatically determining the orientation of the patchin the logical space using the image data includes programmaticallydetermining the orientation of the patch in the logical space usingimage data corresponding to the MRI-visible reference indicator.

Further features, advantages and details of the present invention willbe appreciated by those of ordinary skill in the art from a reading ofthe figures and the detailed description of the preferred embodimentsthat follow, such description being merely illustrative of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are flowcharts representing methods according toembodiments of the present invention.

FIG. 3 is a top perspective view of an exemplary patch assemblyaccording to embodiments of the present invention.

FIG. 4 is an enlarged, fragmentary, cross-sectional view of the patchassembly of FIG. 3 taken along the line 4-4 of FIG. 3.

FIG. 5 is an exploded, top perspective view of the patch assembly ofFIG. 3.

FIGS. 6-15 schematically illustrate an interventional system and/orexemplary operations using the patch assembly of FIG. 3.

FIG. 16 is a top perspective view of a patch assembly according tofurther embodiments of the present invention.

FIG. 17 is a top plan view of a patch according to further embodimentsof the present invention.

FIG. 18 is a top plan view of a patch according to further embodimentsof the present invention.

FIG. 19 is a top plan view of a patch according to further embodimentsof the present invention.

FIG. 20 is a top plan view of a base layer according to furtherembodiments of the present invention, wherein a portion of the baselayer is partially removed.

FIG. 21 is a top perspective view of a patch according to furtherembodiments of the present invention, wherein a tab or component thereofis partially removed.

FIG. 22 is a top perspective view of the patch of FIG. 21, wherein agroup of tabs thereof is partially removed.

FIG. 23 is a plan view of a patch according to further embodiments ofthe present invention.

FIG. 24 is a plan view of a patch according to further embodiments ofthe present invention mounted on a patient's head.

FIG. 25 is a fragmentary, perspective view of a top layer includingMRI-visible tabs according to further embodiments of the presentinvention.

FIG. 26 is a fragmentary, plan view of a base layer according to furtherembodiments of the present invention mounted on a patient's head andwherein a portion of the base layer is partially removed.

FIG. 27 is a plan view of a patch system according to embodiments of thepresent invention mounted on a patient.

FIG. 28 is a data processing system according to embodiments of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which some embodiments of theinvention are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, thethickness of certain lines, layers, components, elements or features maybe exaggerated for clarity.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, steps, operations, elements, components, and/or groupsthereof. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

It will be understood that when an element is referred to as being “on”,“attached” to, “connected” to, “coupled” with, “contacting”, etc.,another element, it can be directly on, attached to, connected to,coupled with or contacting the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being,for example, “directly on”, “directly attached” to, “directly connected”to, “directly coupled” with or “directly contacting” another element,there are no intervening elements present. It will also be appreciatedby those of skill in the art that references to a structure or featurethat is disposed “adjacent” another feature may have portions thatoverlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of “over” and “under”. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly”, “downwardly”, “vertical”, “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Exemplary embodiments are described below with reference to blockdiagrams and/or flowchart illustrations of methods, apparatus (systemsand/or devices) and/or computer program products. It is understood thata block of the block diagrams and/or flowchart illustrations, andcombinations of blocks in the block diagrams and/or flowchartillustrations, can be implemented by computer program instructions.These computer program instructions may be provided to a processor of ageneral purpose computer, special purpose computer, and/or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer and/orother programmable data processing apparatus, create means(functionality) and/or structure for implementing the functions/actsspecified in the block diagrams and/or flowchart block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instructions whichimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer-implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe block diagrams and/or flowchart block or blocks.

Accordingly, exemplary embodiments may be implemented in hardware and/orin software (including firmware, resident software, micro-code, etc.).Furthermore, exemplary embodiments may take the form of a computerprogram product on a computer-usable or computer-readable storage mediumhaving computer-usable or computer-readable program code embodied in themedium for use by or in connection with an instruction execution system.In the context of this document, a computer-usable or computer-readablemedium may be any medium that can contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, or device.

The computer-usable or computer-readable medium may be, for example butnot limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, device, or propagationmedium. More specific examples (a non-exhaustive list) of thecomputer-readable medium would include the following: an electricalconnection having one or more wires, a portable computer diskette, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,and a portable compact disc read-only memory (CD-ROM). Note that thecomputer-usable or computer-readable medium could even be paper oranother suitable medium upon which the program is printed, as theprogram can be electronically captured, via, for instance, opticalscanning of the paper or other medium, then compiled, interpreted, orotherwise processed in a suitable manner, if necessary, and then storedin a computer memory.

Computer program code for carrying out operations of data processingsystems discussed herein may be written in a high-level programminglanguage, such as Java, AJAX (Asynchronous JavaScript), C, and/or C++,for development convenience. In addition, computer program code forcarrying out operations of exemplary embodiments may also be written inother programming languages, such as, but not limited to, interpretedlanguages. Some modules or routines may be written in assembly languageor even micro-code to enhance performance and/or memory usage. However,embodiments are not limited to a particular programming language. Itwill be further appreciated that the functionality of any or all of theprogram modules may also be implemented using discrete hardwarecomponents, one or more application specific integrated circuits(ASICs), or a programmed digital signal processor or microcontroller.

The flowcharts and block diagrams of certain of the figures hereinillustrate exemplary architecture, functionality, and operation ofpossible implementations of embodiments of the present invention. Inthis regard, each block in the flow charts or block diagrams representsa module, segment, or portion of code, which comprises one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the figures. For example, two blocks shown in successionmay in fact be executed substantially.

The term “MRI-visible” means that a device or feature thereof isvisible, directly or indirectly, in an MRI image. The visibility may beindicated by the increased SNR of the MRI signal proximate to the device(the device can act as an MRI receive antenna to collect signal fromlocal tissue) and/or that the device actually generates MRI signalitself, such as via suitable hydro-based coatings and/or fluid(typically aqueous solutions) filled cavities.

The term “MRI-compatible” means that a device is safe for use in an MRIenvironment and/or can operate as intended in an MRI environment, and,as such, if residing within the high-field strength region of themagnetic field, is typically made of a non-ferromagnetic MRI-compatiblematerial(s) suitable to reside and/or operate in a high magnetic fieldenvironment.

The term “programmatically” refers to operations directed and/orprimarily carried out electronically by computer program modules, codeand instructions.

The term “fiducial marker” refers to a marker that can be identifiedvisually and/or using electronic image recognition, electronicinterrogation of MRI image data, or three-dimensional electrical signalsto define a position and/or find the feature or component in 3-D space.

Patches in accordance with embodiments of the present invention can beconfigured to identify or designate a location on a body. The locationmay be identified in order to determine a desired position, orientationor operation of a guide apparatus. The guide apparatus may be used toguide and/or place diagnostic or interventional devices and/or therapiesto any desired internal region of the body or object using MRI and/or inan MRI scanner or MRI interventional suite. The object can be anyobject, and may be particularly suitable for animal and/or humansubjects. In some embodiments, the guide apparatus is used to placeimplantable DBS leads for brain stimulation, typically deep brainstimulation. In some embodiments, the guide apparatus can be configuredto deliver tools or therapies that stimulate a desired region of thesympathetic nerve chain. Other uses inside or outside the brain includestem cell placement, gene therapy or drug delivery for treatingphysiological conditions. Some embodiments can be used to treat tumors.Some embodiments can be used for RF ablation, laser ablation, cryogenicablation, etc. In some embodiments, the interventional tools can beconfigured to facilitate high resolution imaging via intrabody imagingcoils (receive antennas), and/or the interventional tools can beconfigured to stimulate local tissue, which can facilitate confirmationof proper location by generating a physiologic feedback (observedphysical reaction or via fMRI).

In some embodiments, the patch is used to identify a location on thebody for delivering bions, stem cells or other target cells tosite-specific regions in the body, such as neurological target and thelike. In some embodiments, the patch is used to identify a location onthe body for introducing stem cells and/or other cardio-rebuilding cellsor products into cardiac tissue, such as a heart wall via a minimallyinvasive MRI-guided procedure, while the heart is beating (i.e., notrequiring a non-beating heart with the patient on a heart-lung machine).Examples of known stimulation treatments and/or target body regions aredescribed in U.S. Pat. Nos. 6,708,064; 6,438,423; 6,356,786; 6,526,318;6,405,079; 6,167,311; 6539,263; 6,609,030 and 6,050,992, the contents ofwhich are hereby incorporated by reference as if recited in full herein.

Generally stated, some embodiments of the invention are directed to MRIinterventional procedures including locally placing interventional toolsor therapies in vivo to site-specific regions using an MRI system. Theinterventional tools can be used to define an MRI-guided trajectory oraccess path to an in vivo treatment site.

In some embodiments, MRI can be used to visualize (and/or locate) atherapeutic region of interest inside the brain or other body locations,to visualize an MRI-visible patch according to embodiments of thepresent invention, and to visualize (and/or locate) an interventionaltool or tools that will be used to deliver therapy and/or to place achronically implanted device that will deliver one or more therapies.Then, using the three-dimensional data produced by the MRI systemregarding the location of the therapeutic region of interest and thelocation of the interventional tool, the system and/or physician canmake positional adjustments to the interventional tool so as to alignthe trajectory of the interventional tool, so that when inserted intothe body, the interventional tool will intersect with the therapeuticregion of interest. With the interventional tool now aligned with thetherapeutic region of interest, an interventional probe can be advanced,such as through an open lumen inside of the interventional tool, so thatthe interventional probe follows the trajectory of the interventionaltool and proceeds to the therapeutic region of interest.

According to some methods of the present invention and with reference toFIG. 1, a method is provided for identifying a physical location on abody surface (e.g., the scalp) of a patient. A patch is providedincluding a flexible base layer that is mountable on and substantiallyconformable to the body surface and has opposed upper and lower primarysurfaces, a flexible substrate that is releasably attached to the upperprimary surface of the base layer and substantially conformable to thebody surface, and a plurality of MRI-visible fiducial elements definedby or secured to the flexible substrate (Block 60). The MRI-visiblefiducial elements are arranged in a defined pattern. The patch ismounted on the body surface such that the flexible substrate conforms tothe body surface (Block 62). The patient is MRI scanned with the patchon the body surface to generate corresponding image data (Block 64). Aphysical location on the body surface is identified using the image data(Block 66). The flexible substrate is removed from the base layer (Block68). Some embodiments of the present invention include a computerprogram product comprising computer usable program code embodied in acomputer usable medium and configured to programmatically execute thestep of identifying the physical location on the body surface using theimage data.

According to some embodiments of the present invention and withreference to FIG. 2, a method is provided for identifying a physicallocation on a body surface of a patient using a patch mounted on thebody surface. The patch includes a plurality of MRI-visible fiducialelements arranged in a defined pattern. An image of the patient and thepatch in a logical space is generated (Block 70). The image correspondsto an MRI scan of the patient with the patch on the body surface. Adesired trajectory line for insertion of instrumentation into thepatient is determined in the logical space (Block 72). A location ofintersection between the desired trajectory line and the patch isprogrammatically determined (Block 74). In some embodiments, thelocation of intersection is visually displayed. Some embodiments of thepresent invention include a computer program product comprising computerusable program code embodied in a computer usable medium and configuredto programmatically determine the location of intersection between thedesired trajectory line and the patch.

With reference to FIGS. 1-5, an integral patch assembly 101 according toembodiments of the present invention is shown therein. The patchassembly 101 includes a patch 100 and a release liner 102. The patch 100includes a base substrate or layer 110, a primary or base adhesive 120,an MRI-visible or top substrate or layer 130, and a secondary or topadhesive 122.

With reference to FIGS. 4 and 5, the base layer 110 has opposed upperand lower primary surfaces 112A, 112B. The base adhesive 120 coats thelower primary surface 112B. The release liner 102 is releasably adheredto the base layer 110 by the base adhesive 120, which remains with thebase layer 110 when the release liner 102 is removed. The release line102 may include a pull tab 102A. Optionally, the base layer 110 mayinclude a pull tab 114 free of the adhesive 120.

The base layer 110 is formed of a flexible material. According to someembodiments, the base layer 110 is formed of a biocompatible polymericmaterial suitable for surgical use in MRI systems. Suitable polymericmaterials may include polyvinyl, PET, silicone, polyethylene,polyurethane, and/or polyamide.

According to some embodiments, the base layer 110 has a thickness in therange of from about 0.001 to 0.100 inches. According to someembodiments, the base layer 110 has a total area in the range of fromabout 1 to 900 cm².

According to some embodiments, the base adhesive 120 is a biocompatibleadhesive that has adhesive properties that ensure a secure, butreleasable, bond with human skin and/or an incise drape.

With reference to FIGS. 3 and 4, the top layer 130 has an integral,bilayer construction including an inner layer 134 and an outer layer136. However, other constructions in accordance with aspects of theinvention are contemplated, as well. The top layer 130 has a lowersurface that is coated with the top adhesive 122. The top layer 130includes a pull tab 138 extending beyond an edge thereof. A portion orall of the pull tab 138 may be free of the adhesive 122.

The outer layer 136 is attached to the inner layer 134 at seams 144(FIG. 4) to form a plurality of discrete pockets or cavities 142 (FIG.4) between the seams 144 and the layers 134, 136. The layers 134, 136may be attached via any suitable means such as bonded by adhesive, heatbonding or any other suitable technique. Each pocket 142 is filled witha mass 146 (FIG. 4) of an MRI-visible material 146 to form a respectiveMRI-visible fiducial element, bubble or tab 140. The plurality of tabs140 can be arranged in a predefined array 168 and include a referencetab 140R (FIG. 3) positioned or shaped to be readily discerned withrespect to the other tabs. While MRI-visible tabs 140, 140R areillustrated and described, other types and construction of MRI-visiblefiducial elements may be employed in accordance with furtherembodiments. For example, the reference tab 140R may be replaced orsupplemented with an MRI-visible coating.

The layers 134, 136 are formed of a flexible material. According to someembodiments, the layers 134, 136 are formed of a polymeric material.Suitable polymeric materials may include polyvinyl, PET, silicone,polyethylene, polyurethane, and/or polyamide.

The MRI-visible material 146 may be any suitable material. According tosome embodiments, the MRI-visible material 146 is a liquid. According tosome embodiments, the MRI-visible material 146 includes sterile salineor water (e.g., deionized water), with or without vitamin E and/orGadolidium.

According to some embodiments, each pocket 142 has a volume in the rangeof about 50 to 500 microliters. According to some embodiments, eachpocket 142 has a nominal height in the range of from about 0.010 to 1inch. According to some embodiments, each pocket 142 has an area in therange of from about 4 mm² to 4 cm².

According to some embodiments, the top layer 130 has a nominal thicknessin the range of from about 0.001 to 0.1 inch. According to someembodiments, the top layer 130 has a total area in the range of fromabout 1 to 900 cm².

According to some embodiments, the top adhesive 122 is a biocompatibleadhesive that has adhesive properties that ensure a secure, butreleasable bond with base layer 110.

The MRI-visible tabs 140 can be arranged in a defined pattern 163 (FIG.3). According to some embodiments and as illustrated, the definedpattern 163 is a grid pattern, wherein the grid is demarcated by thevoids between the masses 146 of MRI-visible material (generally, theseams 144). The defined pattern 163 defines a coordinate system 161. Thecoordinate system 161 may be codified in any suitable manner. Forexample, as illustrated, letter indicia 164 (i.e., “A” to “J”) areprovided to designate respective rows of the tabs 140 and number indicia166 (i.e., “1” to “10”) are provided to designate respective columns ofthe tabs 140 in the coordinate system 161. However, other markings orindicators as well as other languages may be used.

According to some embodiments, the predefined tab array 168 includes agrouping of at least five-by-five tabs 140.

The reference tab 140R of the tab array 140 is positioned to indicate anorientation of the top layer 130. According to some embodiments, thereference tab 140R (or other reference MRI-visible fiducial element) hasa shape that is discernibly dissimilar from the other tabs 140 in an MRimage. In this case, the reference tab 140R may not be positioned toindicate the orientation, but rather the orientation may be indicated bythe orientation of the reference tab 140R.

Base indicia 150 (FIG. 5) can be provided on the base layer 110 anddefine a prescribed pattern and a corresponding coordinate system 151that in turn corresponds to the coordinate system 161. The base indiciamay be provided on the base layer 110 by etching, printing, molding,embossing, stamping, pressing or any other suitable technique. Accordingto some embodiments and as illustrated, the base indicia 150 includegrid lines 152 defining a matrix or grid 153 of sectors 152A. Letterindicia 154 (i.e., “A” to “J”) are provided to designate respective rowsof the sectors 152A and number indicia 156 (i.e., “1” to “10”) areprovided to designate respective columns of the sectors 152A. Foursubsector marks 158 (as shown, cross-hairs or grid lines) are providedin each sector 152A to designate quadrants of the sector 152A.

Greater on lesser numbers of rows, columns, markers, and subsectors maybe provide.

The indicia 154, 156 serve as codified indicia representing orcorresponding to the coordinate system 161 of the tab array 168. Each ofthe sectors 152A may be sized and positioned to substantiallycoextensively align with a respective matched or overlying one of thetabs 140. The prescribed pattern of the base indicia 150 has higherresolution than the defined pattern of the array 168 of MRI-visible tabs140 because the base indicia 150 further include the subsector marks 158in each sector 152A.

Operations associated with an exemplary surgical procedure using thepatch assembly 101, according to some embodiments of the presentinvention, will now be described with further reference to FIGS. 6-15.These operations relate to deep brain stimulation procedures.Embodiments of the present invention are not limited to use with deepbrain stimulation procedures, however, and may be suitable for othersurgical uses including robotic or other type of intrabody surgeries.

With reference to FIG. 7, the operations may be executed on a head 12 ofa patient 10 using a patch assembly 101 as described above and aninterventional system 15. The system 15 includes or is in communicationwith an MRI scanner 20, a display 22, an electronic controller 24, auser interface 26, a trajectory guide apparatus 44 (FIG. 15), and adevice controller 44A (FIG. 15). The controller 24 may include atrajectory guide module 24B and a patch recognition module 24A (whichmay be software or firmware modules, for example).

The controller 24 may be any suitable computer(s) or the like adapted tocarry out the functions described herein. The user interface 26 mayinclude a man-machine interface to enable an operator to access andcontrol operations of the system 15. The controller 24 can be operablyconnected to each of the display 22 and the MRI scanner 20.

The surface of the patient's head 12 is suitably prepared by shaving andcleaning, for example. The release liner 102 is peeled away from thebase layer 110 to expose the base adhesive 120 (FIG. 6). The patch 100is applied to the surface of the head 12 such that the flexible layers110, 134, 136 conform to the head surface and the patch 100 is adheredto the head surface by the base adhesive 120 (FIG. 7). An incise drapeor the like may be pre-applied to the skin surface and the patch 100 inturn applied to the incise drape, in which case the patch 110 maylikewise be regarded as being mounted on the surface of the head (albeitindirectly). The patch 100 is applied at a location such that the gridpattern 161 spans the region wherein the operator expects to enter thehead 12 with an interventional tool or device.

With the patch 100 adhered to the patient's head 12, the patient isplaced within an MRI scanner 20. The MRI scanner scans the head 12 andgenerates corresponding MR image data. From the MR image data, MR imagesare obtained of the patient's head that visualize the patient's skulland brain. The MR images also visualize the MRI-visible masses 146 ofthe patch 100, which serve as MRI-visible landmarks. The MR images caninclude volumetric high-resolution images of the brain.

With reference to FIG. 8, a target region TR (which may also be referredto as a region of interest or target therapeutic site) in the head 12 isidentified in the MR images. To identify the target region TR, certainknown anatomical landmarks can be used. For example, reference may bemade to physiological landmarks such as the AC, PC and MCP points (brainatlases give the location of different anatomies in the brain withrespect to these points) and other anatomical landmarks of the patient'shead.

A target point TP within the target region TR is selected and designatedin a logical space in the MR image. A planned trajectory line PTL isselected and designated extending from the target point TP to a desiredreference point (such as an operative pivot point of the trajectoryguide apparatus 44 discussed hereinbelow). The planned trajectory linePTL extends through an entry surface of the head 12 at a desired entrylocation point EP in the logical space. According to some embodiments,the pivot point is located at or proximate the entry location point EP.Images are obtained in the planned plane of trajectory to confirm thatthe trajectory is viable (i.e., that no complications with anatomicallysensitive areas should occur). The steps of identifying the targetregion TR, identifying the target point TP, and/or selecting anddesignating the planned trajectory line PTL may be executed using orwith the aid of the trajectory guide module 24B, for example.

A point of intersection IP between the logical planned trajectory linePTL and the patch 100 in the logical space is determined. Moreparticularly, according to some embodiments, the point of intersectionIP between the planned trajectory line PTL and the array 168 ofMRI-visible masses 146 is determined.

The intersection point IP may be determined by visually displaying thesame on the display 22 where it can be readily identified by theoperator (for example, as shown in FIG. 9A). For example, arepresentation or highlight of the planned trajectory line PTL and/orthe intersection point IP can be programmatically determined by thecontroller 24 and overlaid or projected onto an image 30 of the tabarray 168. The image 30 may further include the MR image of the patientand/or an overlaid representation of the target point TP. The operatorcan determine the coordinates of the intersected tab 140 by determiningthe row number and column number of the tab 140 in the array 168 (FIG.1), for example.

Alternatively or additionally, the controller 24 may programmaticallyidentify or recognize and analyze and/or report the MRI-visible masses146 in the image data.

According to some embodiments, the controller 24 (e.g., using the patchrecognition module 24A) processes the acquired image data toprogrammatically recognize, orient and place the patch 100 in thelogical space. According to some embodiments, the controller 24 uses analgorithm to programmatically determine the position of the tab array168 in the logical space. According to some embodiments, the controlleruses a pre-stored reference image or images to programmaticallydetermine the position of the tab array 168 in the logical space.

Once the controller 24 has assessed the position (e.g., includingorientation) of the patch 100 in the logical space, the controller 24can use this data to identify the intersection point IP or enable orassist identification of the intersection point IP by the operator. Forexample, the controller 24 may enhance (e.g., add increased imagecontrast) or insert highlighted representations of the tabs 140 into theimage 30 as provided on the display 22 in order to make the intersectedtab 140 and/or the tab array 168 visually stand out in the image 30.

According to some embodiments, the controller 24 generates, fits andoverlays or superimposes a graphical grid overlay 31 onto the MR image30 as shown in FIG. 9B, for example, to delineate the location anddistribution of the patch 100 on the head. The positions andorientations of the patch 100 and the MRI-visible tab may be correlatedto the image of the head 12 by the graphical grid overlay 31. Accordingto some embodiments, the graphical grid overlay 31 is fitted to thecontours of the patch 100 in three dimensional space as illustrated, forexample. This may be accomplished by segmenting the image of the tabarray 168 and incorporating assessed angle data (of the edges of thetabs 140) in the process of drawing and fitting the graphical gridoverlay 31.

The controller 24 may determine and report or indicate the coordinatesfrom the grid 163 corresponding to the intersection point IP to theoperator (e.g., visually via the display 22 and/or audibly via a soundtransducer). For example, in FIG. 9A, the intersection point IP islocated in the MRI-visible tab 140 located in column 5 and row C of thegrid 163, and the graphical representation of the intersection point IPis labeled in the image 30 with these coordinates (as illustrated, “(7,D)”, designating the tab 140 at column “7” and row “D”) and a graphicoverlay 32. The operator and/or the controller 24 can also determine theportion or region (e.g., quadrant) of the tab 140 within which theintersection point IP resides.

The reference tab 140R can be identified in the image 30 and used by theoperator and/or the controller 24 to determine and register theorientation of the coordinate system 161 of the patch 100 in the logical(i.e., MR volume) frame of reference.

The controller 24 can provide various additional functionality once ithas recognized the tab array 168 in the MR image 30. According to someembodiments, the controller 24 will issue an alert (e.g., visible oraudible) to the operator if the planned trajectory line PTL does notintersect the grid 163. According to some embodiments, the controller 24will initially position a provisional planned trajectory line throughthe center of the grid 163. The operator can then move the provisionalplanned trajectory line in the display as needed to arrive at thedesired ultimate planned trajectory line PTL.

The physical location on the top layer 130 corresponding to theintersection point IP can be readily determined using the image from theMR image data (e.g., by comparison to the image of the tabs 140 in theMR image and/or by reference to the coordinate system 161). Because thetop layer 130 is affixed to the head 12 and the relationship between thepatient's scalp and the MRI-visible tabs 140 is thereby maintained, thephysical location of the intersection point IP (and, thus, the entrylocation point EP) can likewise be readily identified.

According to some embodiments and as illustrated, the thickness of thepatch 100 between the tabs 140 and the underlying surface of the head 12is thin (e.g., no more than 0.003 and 0.100 inch) so that theintersection point IP between the planned trajectory line PTL and thearray 168 is substantially the same or closely proximate theintersection point between the planned trajectory line PTL and thesurface of the head 12.

Once the MR image(s) have been acquired for determining the intersectionpoint IP, the patient can be withdrawn from the scanning apparatus 20 tofacilitate access to the patient's head 12. The operator removes the toplayer 130 from the base layer 110 to reveal the base layer 110 bylifting an edge of the top layer 130 and peeling the top layer 130 awayfrom the base layer 110 as shown in FIG. 10, for example.

With the base layer 110 remaining on the head 12 and exposed, theoperator identifies the location (referred to herein as the label pointLP) on the base layer 110 corresponding to the location of theintersection point IP in the top layer 130. This identification may beenabled by a prescribed correspondence between the coordinate system 151of the base layer 110 and the array 168 of MRI-visible tabs 140 (FIG.5). For example, in the foregoing step, the operator may determine thatthe intersection point IP was located in the top, right quadrant of thetab 140 located at column “5”, row “C” of the array 168. The operatorcan, in the present step, locate the quadrant located in the top, rightquadrant of the square sector 152A (FIG. 5) located at column “5”, row“C” of the coordinate system 151 and identify this quadrant as thecorresponding label point LP. According to some embodiments, thecoordinate system 151 (FIG. 5) is readily legible on the base layer 110so that the operator can expeditiously and reliably identify the labelpoint LP without special tools or cumbersome procedure.

Having identified the label point LP, the operator may thereafter markthe head 12 at a location on the head surface corresponding to the labelpoint LP. According to some embodiments, the operator marks the headsurface at a location immediately below the label point LP. It will beappreciated that this location on the head surface is substantially thesame as the intended entry location point EP designated above for theplanned trajectory line PTL. The patch 100 thus can provide precisecorrelation between the logical points in the scanned MR volume and thephysical patient.

The operator can mark the head 12 at or proximate the desired entrylocation using a suitable tool or implement. According to someembodiments and as shown in FIG. 11, the operator uses a marking tool 40in the form of a driver. The operator presses the marking tool 40 intothe patient's head 12 such that the marking tool 40 penetrates throughthe skin and may partially penetrate into the skull. The marking tool 40may be driven through the base layer 110 and into the head 12.Alternatively, the operator may lift or remove a portion of the baselayer 110 to expose the location on the scalp to be marked and then markthe scalp. A visually identifiable mark 14 (FIG. 13) will thereafterremain in the patient's scalp and/or skull for the physician'sreference. Suitable marking tools may include marking tools as disclosedin co-assigned U.S. Provisional Patent Application No. 61/041,500, thedisclosure of which is incorporated herein by reference. Alternatively,the operator may mark the scalp with ink or other suitable material.

The base layer 110 is removed (e.g., peeled away) from the head 12 asshown in FIG. 12.

A burr hole 16 (FIG. 14) can thereafter be formed in the head 12 at thelocation of the mark 14 using any suitable technique or device (e.g.,drilling). A burr hole ring 42 (FIG. 14) may be affixed to the skull 12overlying the burr hole 16.

The procedure may thereafter be continued using the burr hole 16 as anaccess portal to the brain and employing suitable instrumentation suchas the trajectory guide apparatus 44. The trajectory guide apparatus 44can be fixed to the skull of the patient as shown in FIG. 15, forexample. The trajectory guide apparatus 44 may allow the operator toalign an access path trajectory to the internal target site TP, suchthat the interventional/surgical device/lead, therapy, etc. will bedelivered to the target site following the desired trajectory (e.g., theplanned trajectory line PTL) through the cranial tissue. This trajectorygoes through the entry location point EP. The interventional device(e.g., probe, lead or the like) can be advanced through a targetingcannula 44B of the trajectory guide apparatus 44, into the head 12 andto or proximate the target point TP. In some embodiments, the trajectoryguide apparatus 44 can pivot the targeting cannula 44B about a pivotpoint at or proximate the entry point location EP. The trajectory guideapparatus 44 may be remotely repositioned using a trajectory guideapparatus controller 44A, for example. Suitable trajectory guideapparatus and methods may include those disclosed in co-assigned PCTApplication No. PCT/US2006/045752 and co-assigned U.S. patentapplication Ser. No. 12/134,412, the disclosures of which areincorporated herein by reference.

In some embodiments, the controller 24 is in communication with agraphical user interface (GUT) that allows a clinician to define adesired trajectory and/or end position on a displayed image, then canelectronically convert the orientation/site input data programmaticallyto generate position data for the trajectory guide apparatus 44. The GUIcan include an interactive tool that allows a clinician to draw, traceor otherwise select and/or identify the target treatment site and/oraccess path trajectory. The system 15 can then be configured to identifyadjustments to the trajectory guide apparatus 44 that are most likely toachieve this trajectory.

In some embodiments, the user interface 26 can be configured toelectronically determine the location of a targeting cannula and atrajectory associated therewith. The user interface 26 can be configuredto display MRI images with the planned trajectory and intersectionpoint(s) that will be followed if the interventional/surgicaldevice/lead is advanced using a defined position of the trajectory guideapparatus 44.

According to some embodiments the patch assembly 101 is packaged as amedical kit with the marking tool 40. The patch assembly 101 may be usedin conjunction with a burr hole forming tool (e.g., a drill) configuredto drill, cut or otherwise form a burr hole through the patient's skull12. According to some embodiments, the marking tool 40 and the burr holeforming tool are formed of MRI-compatible materials.

With reference to FIG. 16, a patch assembly 201 according to furtherembodiments of the present invention is shown therein. The patchassembly 201 corresponds to the patch assembly 101 except that the tabs240C of the center row and the center column of the tab array 268 have ageometric shape (as shown, circular) different than the geometric shape(as shown, rectangular) of the remaining tabs 240. The respective shapesare distinguishable from one another when observed in the MR image. Thiscombination of dissimilar tab shapes may assist the operator orcontroller 24 in identifying the location of the tab 240 or 240Cintersecting the planned trajectory line PTL.

With reference to FIGS. 17-19, patches 300, 400, 500 according tofurther embodiments of the present invention are shown therein. Thepatches 300, 400, 500 each correspond to the patch 100 except that theyfurther include perforations extending through the top layers 330, 430,530 thereof between the tabs 340, 440, or 540. As illustrated, in someembodiments, the perforations may be configured as closed slits 339,circular holes 439, or open, elongated slots 539. In use, theperforations may help the top layer 330, 430, 530 to conform to thepatient's head. The base layers 310, 410, 510 may also includeperforations (e.g., extending along the grid lines) to help the baselayer 310, 410, 510 conform to the patient's head. According to someembodiments, reliefs that do not extend fully through the top layer 330,430, 530 may be used in place of the perforations.

With reference to FIG. 20, a base layer 610 according to furtherembodiments of the present invention is shown therein. The base layer610 may be used in place of the base layer 110 for the patch 100, forexample, and corresponds to the base layer 110 except as follows. Thebase layer 610 can include a grid of perforations 614 generallycoextensive with the grid of the base coordinate system 651. The baselayer 610 may be used in the same manner as the base layer 110 exceptthat the operator may selectively tear away or remove a section of thebase layer 610 along the perforations 614 in order to expose theunderlying scalp for marking with the marking tool. According to furtherembodiments, the base layer 110 may be rendered frangible by score linesor other suitable features.

With reference to FIGS. 21 and 22, a patch 700 according to furtherembodiments of the present invention is shown therein. The patch 700corresponds to the patch 100 except that the tabs 740 thereof can beremoved individually or in subgroups from the remainder or the top layer730. In use, the operator can remove a selected one or ones of the tabs740 from the patient's head to reveal the underlying base layer 710. Thebase layer 710 may also be frangible (e.g., including perforationscorresponding to the perforations 614), in which case the underlyingsegment of the base layer 710 may also be selectively removed to exposethe patient's scalp for marking. Indicia 755 may be visible on the baselayer 710 where the tabs 740 have been removed.

With reference to FIG. 23, a patch 800 according to further embodimentsof the present invention is shown therein. The patch 800 may correspondto the patch 100 except that the tab array 868 of the patch 800 includesrows of MRI-visible tabs 840G, 840H, 840I having distinctly differentgeometric shapes (as shown, a circular shape, a square shape, and atriangular shape, respectively). The different tab shapes arediscernable from an MR image of the patch 800 by an operator and/or thecontroller 24. The configuration of the tab array 868 may facilitatedetermination of the orientation of the patch 100 in logical spaceand/or identification of the tab 840G, 840H, 840I intersected by theplanned trajectory line PTL.

With reference to FIG. 24, a patch 900 according to further embodimentsof the present invention is shown therein. The patch 900 may correspondto the patch 100 except that the patch 900 includes a mesh (“fishnet”)substrate 930 to which an array 968 of MRI-visible tabs 940(corresponding to the tabs 140) are secured. The substrate 930 can beelastic or stretchable to readily deform or conform to the contours of ahead 12. The patch 900 may be used in the same manner as the patch 100except that in some embodiments the patch 900 may not include any baselayer corresponding to the base layer 110. In this case, the operatormay identify and mark the desired location (e.g., the point ofintersection IP) through the openings 930A of the mesh substrate 930 andthe mesh substrate 930 may be adhered directly to the head (or an incisedrape) by adhesive on the back surface of the mesh substrate 930. Thecontroller 24 may recognize and assess the tab array 968 and construct amodified grid in logical space that corresponds to the distorted orirregular distribution of the tabs 940 caused by the stretching ofsubstrate 930. The controller 24 may recognize and assess the tab array968 and construct a modified grid in logical space that corresponds tothe distorted or irregular distribution of the tabs 940 caused by thestretching of the substrate 930. According to still further embodiments,the layers 110 and 130 of the patch 100 may be stretchable (with orwithout being meshes) to enable similar stretchable conformability tothe head 12.

With reference to FIG. 25, a top layer 1030 according to furtherembodiments of the present invention is shown therein. The top layer1030 may be used in place of the top layer 130, for example. The toplayer 1030 differs from the top layer 130 in that the top layer 1030includes MRI-visible tabs 1040 each having a height dimension H1 greaterthan its width W1. The height of each tab 1040 is sufficient to permitthe controller 24 and/or an operator to determine the orientation of aheightwise axis AH-AH of the tab 1040. This additional information canbe employed to more accurately assess the point of intersection IP withthe planned trajectory line PTL.

With reference to FIG. 26, a base layer 1110 according to furtherembodiments of the present invention is shown therein. The base layer1110 may be used in place of the base layer 110 or the base layer 610,for example. The base layer 1110 differs from the base layer 610 in thatthe base layer 1110 includes a supply of ink 1180 therein and/orthereon. When the base layer 1110 is applied to the head 12, the ink1180 transfers to the head 12 to leave an ink pattern 1182 on thesurface of the head. For example, the ink pattern 1182 can include afull or partial duplicate 1182A of the grid lines 1152 on the base layer1110 and/or textual or codified indicia 1182B indicating thecoordinates. The base layer 1110 can be used in the same manner as thebase layer 110 or the base layer 610 except that the base layer 1110 canbe fully or partially removed prior to marking the head 12 with amarking tool or the like. In this case, the ink pattern 1182 remains onthe scalp to assist the operator in marking the physical locationcorresponding to the intersection point IP determined from the MR image30.

The ink 1180 may be any suitable material that can transfer from thebase layer 1110 to the patient's scalp, bond or adhere to the scalp, andprovide a suitably visible contrast with the scalp. The ink may be aliquid or powder, for example.

According to further embodiments, the ink supply may be provided in oron the substrate including the MRI-visible tabs (e.g., the top layer130) in which case the base layer (e.g., the base layer 110) can beomitted. The substrate can be removed after the MRI scan is taken,leaving the ink pattern on the scalp of the head 12 to provide thereference grid on the head 12 for locating the physical location of theintersection point IP.

With reference to FIG. 27, a patch system 1203 and method according tofurther embodiments of the present invention are illustrated therein.The patch system 1203 includes a plurality of the patches 100, forexample, applied to the patient 12 in close proximity to one another toform a patch array 1208. The patches 100 may be tiled together (i.e.,placed in close proximity to one another) and may or may not beimmediately adjacent one another or overlapping. The patch system 1203may be used in generally the same manner as the patch 100 as describedabove, except that the patch system 1203 will cover a greater surfacearea on the patient and only one of the patches 100 thereof will beintersected by the planned trajectory line PTL. The operator mayvisually determine which of the patches contains the intersection pointIP and where the intersection point IP lies in the patch. According tosome embodiments, the controller 24 programmatically assesses the patchsystem 1203 in the MR image to determine and indicate, report orotherwise process the positions of the patches 100 as discussed abovewith regard to the patch 100. The controller 24 may correlate theplurality of patches 100 with respect to one another so that the patchsystem 1203 can be assessed and processed in substantially the samemanner as the single patch 100. The controller 24 may programmaticallyaccount for variations resulting from relative placements of the patches100 in the patch array 1208. According to some embodiments, thecontroller 24 determines the orientation of each patch 100 using eachpatch's respective reference tab 140R as described above.

Still further embodiments of the present invention may incorporateaspects or features as described herein in other forms, combinationsand/or applications. For example, a flexible substrate havingselectively removable MRI-visible tabs (such as the substrate 730 andthe tabs 740) may be provided without a base layer (e.g., the base layer710) and may be directly applied to a patient's body surface or incisedrape.

By way of further example, a patch may be provided having a base layer(e.g., corresponding to the base layer 110) and a removable top layer(e.g., corresponding to the top layer 130), but wherein the top layercarries only a single (i.e., exactly one) MRI-visible fiducial elementor tab. The single MRI-visible fiducial element may have an asymmetricshape that is discernable in an MRI image so that the orientation of thepatch in the logical space can be determined from the MRI image data.According to some method embodiments, the orientation of a patch (withor without a base layer) having only a single MRI-visible fiducialelement is programmatically determined (e.g., by the controller 24) fromthe MRI image data. According to still further embodiments, the patch(with our without a base layer) may have a plurality of MRI-visiblefiducial elements, but wherein the fiducial elements are not arranged ina defined pattern.

Two patches (or groups of patches) in accordance with the presentinvention (e.g. two of the patches 100) can be employed together toidentify and mark two entry location points for a bilateral surgicalprocedure on a patient's head. The two patches 100 may be concurrentlymounted on the head and each patch used in the same manner as discussedabove. In this case, the controller 24 may programmatically distinguishbetween the two patches and their respective planned trajectory linesPTL so that the point of intersection IP for each patch can bedetermined independently of the other. The controller 24 maysimultaneously display the patches 100 and their associated points ofintersection IP, planned trajectory lines PTL, graphical overlays andthe like.

The system 15 (FIG. 7) can include circuits or modules that can comprisecomputer program code used to automatically or semi-automatically carryout operations to generate multi-dimensional visualizations during anMRI guided therapy. FIG. 28 is a schematic illustration of a circuit ordata processing system 80 that can be used with the system 15. Thecircuits and/or data processing systems 80 data processing systems maybe incorporated in a digital signal processor in any suitable device ordevices. As shown in FIG. 28, the processor 82 communicates with an MRIscanner 20 and with memory 84 via an address/data bus 85. The processor82 can be any commercially available or custom microprocessor. Thememory 84 is representative of the overall hierarchy of memory devicescontaining the software and data used to implement the functionality ofthe data processing system. The memory 84 can include, but is notlimited to, the following types of devices: cache, ROM, PROM, EPROM,EEPROM, flash memory, SRAM, and DRAM.

As shown in FIG. 28 illustrates that the memory 84 may include severalcategories of software and data used in the data processing system: theoperating system 86; the application programs 88; the input/output (I/O)device drivers 92; and data 90. The data 90 can also include tool andpatient-specific image data 90A. FIG. 28 also illustrates theapplication programs 88 can include the patch recognition module 24A andthe trajectory guide module 24B.

As will be appreciated by those of skill in the art, the operatingsystems 452 may be any operating system suitable for use with a dataprocessing system, such as OS/2, AIX, DOS, OS/390 or System390 fromInternational Business Machines Corporation, Armonk, N.Y., Windows CE,Windows NT, Windows95, Windows98, Windows2000 or other Windows versionsfrom Microsoft Corporation, Redmond, Wash., Unix or Linux or FreeBSD,Palm OS from Palm, Inc., Mac OS from Apple Computer, LabView, orproprietary operating systems. The I/O device drivers 92 typicallyinclude software routines accessed through the operating system 86 bythe application programs 88 to communicate with devices such as I/O dataport(s), data storage 90 and certain memory 84 components. Theapplication programs 88 are illustrative of the programs that implementthe various features of the data processing system and can include atleast one application, which supports operations according toembodiments of the present invention. Finally, the data 90 representsthe static and dynamic data used by the application programs 88, theoperating system 86, the I/O device drivers 92, and other softwareprograms that may reside in the memory 84.

While the present invention is illustrated, for example, with referenceto the modules 24A-24B being application programs in FIG. 28, as will beappreciated by those of skill in the art, other configurations may alsobe utilized while still benefiting from the teachings of the presentinvention. For example, the modules 24A, 24B and/or may also beincorporated into the operating system 86, the I/O device drivers 92 orother such logical division of the data processing system. Thus, thepresent invention should not be construed as limited to theconfiguration of FIG. 28 which is intended to encompass anyconfiguration capable of carrying out the operations described herein.Further, one or more of modules, i.e., modules 24A, 24B can communicatewith or be incorporated totally or partially in other components, suchas an MRI scanner.

The I/O data port can be used to transfer information between the dataprocessing system, the MRI scanner, the tool and another computer systemor a network (e.g., the Internet) or to other devices controlled by theprocessor. These components may be conventional components such as thoseused in many conventional data processing systems, which may beconfigured in accordance with the present invention to operate asdescribed herein.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. The invention is defined by the following claims, withequivalents of the claims to be included therein.

1. An MRI-compatible patch for identifying a location, the patchcomprising: a flexible base layer that is mountable on and substantiallyconformable to a patient's body surface, the base layer having opposedupper and lower primary surfaces; a flexible substrate that isreleasably attached to the upper primary surface of the base layer andsubstantially conformable to the patient's body surface; a plurality ofMRI-visible fiducial elements defined by or secured to the flexiblesubstrate, wherein the MRI-visible fiducial elements are arranged in adefined pattern; and indicia on the base layer corresponding to theMRI-visible fiducial elements on the flexible substrate, wherein theindicia has a second prescribed pattern having a higher resolution thanthe defined pattern of the MRI-visible fiducial elements on the flexiblesubstrate.
 2. The patch of claim 1 including a layer of adhesivedisposed on a lower surface of the flexible substrate and engaging theupper primary surface of the base layer and releasably attaching theflexible substrate to the base layer.
 3. The patch of claim 1 includingan adhesive disposed on the lower primary surface of the base layer toattach the base layer to the body surface.
 4. The patch of claim 3including a release liner releasably backing the adhesive on the lowerprimary surface of the base layer.
 5. The patch of Claim 1 includingsecond indicia on the flexible substrate corresponding to the indicia onthe base layer.
 6. The patch of Claim 1 wherein the defined patternincludes a grid pattern defining a coordinate system.
 7. The patch ofclaim 6 including codified indicia representing the coordinate system.8. The patch of claim 6 wherein the MRI-visible fiducial elements arediscrete elements arranged in a defined grid of columns and rows of theMRI-visible fiducial elements.
 9. The patch of claim 1 wherein theflexible substrate includes a pull tab to facilitate removal of theflexible substrate from the base layer.
 10. The patch of claim 1 whereinthe base layer is frangible to permit selective access to the bodysurface when the base layer is mounted thereon and the flexiblesubstrate has been at least partially removed.
 11. The patch of claim 1including at least one MRI-visible reference indicator to indicate anorientation of the patch.
 12. The patch of Claim 1 wherein at least oneof the MRI-visible fiducial elements has a first MRI-visible geometricshape, and at least one of the MRI-visible fiducial elements has asecond MRI-visible geometric shape different from the first MRI-visiblegeometric shape.
 13. The patch of Claim 1 wherein at least some of theMRI-visible fiducial elements include a pocket containing MRI-visiblematerial.
 14. The patch of claim 13 wherein the MRI-visible materialincludes an MRI-visible liquid.
 15. The patch of Claim 1 wherein atleast some of the MRI-visible fiducial elements are selectivelydiscretely removable from the flexible substrate.
 16. The patch of claim1 including perforations defined in the flexible substrate to therebyenhance conformity of the flexible substrate to the body surface. 17.The patch of claim 1 wherein the flexible substrate is formed of astretchable material to allow the flexible substrate to conform to ahead body surface.
 18. The patch of claim 1 wherein the flexiblesubstrate is a mesh.
 19. The patch of claim 1 including a supply of inkthat is transferable to the patient's body surface when the patch ismounted on the patient's body surface.
 20. The patch of claim 1 whereinat least one of the MRI-visible fiducial elements has a width and aheight greater than its width to define a heightwise axis.
 21. The patchof claim 1 wherein the flexible substrate has a thickness in the rangeof from about 0.001 to 0.100 inches.
 22. The patch of claim 1 whereinthe flexible substrate is a substrate material selected from the groupconsisting of polyvinyl, PET, silicone, polyethylene, polyurethane, andpolyamide.
 23. The patch of claim 1 further including: an adhesivedisposed on the lower primary surface of the base layer adapted toattach the base layer to the body surface; a release liner releasablysecured to the adhesive on the lower primary surface of the base layer;and at least one MRI-visible reference indicator to indicate anorientation of the patch; wherein at least some of the MRI-visiblefiducial elements include a pocket containing MRI-visible liquid; andwherein the defined pattern includes a grid pattern defining acoordinate system.
 24. The patch of claim 23 wherein: the patch includesa layer of adhesive disposed on a lower surface of the flexiblesubstrate and engaging the upper primary surface of the base layer andreleasably attaching the flexible substrate to the base layer; theindicia represents the coordinate system; the base layer and theflexible substrate are adapted to be substantially conformable to a headbody surface of the patient; the flexible substrate has a thickness inthe range of from about 0.001 to 0.100 inches; and the flexiblesubstrate is a substrate material selected from the group consisting ofpolyvinyl, PET, silicone, polyethylene, polyurethane, and polyamide. 25.The patch of claim 1 wherein the flexible substrate includes a flexiblesheet and the MRI-visible fiducial elements are releasably secured tothe flexible sheet.
 26. The patch of claim 25 including a layer ofadhesive disposed on a lower surface of the flexible sheet and engagingthe upper primary surface of the base layer and releasably attaching theflexible sheet to the base layer.
 27. The patch of claim 25 wherein theflexible sheet is peelably releasably attached to the base layer suchthat the flexible sheet can be peeled off of the base layer with theMRI-visible fiducial elements disposed on the flexible sheet.
 28. Amedical kit for designating a physical location on a head of a patient,the medical kit comprising: a patch including: a flexible base layerthat is mountable on and substantially conformable to a patient's bodysurface, the base layer having opposed upper and lower primary surfaces;a flexible substrate that is releasably attached to the upper primarysurface of the base layer and substantially conformable to the patient'sbody surface; a plurality of MRI-visible fiducial elements defined by orsecured to the flexible substrate, wherein the MRI-visible fiducialelements are arranged in a defined pattern; and indicia on the baselayer corresponding to the MRI-visible fiducial elements on the flexiblesubstrate, wherein the indicia has a second prescribed pattern having ahigher resolution than the defined pattern of the MRI-visible fiducialelements on the flexible substrate; and a head marking tool beingconfigured to mark the head of the patient.
 29. The medical kit of claim28 wherein the head marking tool is configured to mark a skull of thepatient.